This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Digital broadband broadcast networks enable end users to receive digital content including video, audio, data, etc. Using a portable, mobile or fixed terminal, a user may receive digital content over a wireless digital broadcast network. Digital content can be transmitted in a cell within a network. A cell may represent a geographical area that may be covered by a transmitter in a communication network. A network may have multiple cells and cells may be adjacent to other cells.
In the Digital Video Broadcasting (DVB)-T2 standard, a method has been proposed for transmitting data over several separate radio frequency (RF) channels. In the method, data path error resiliency is improved because error correction is performed over several RF channels that are independent on each other.
In systems such as DVB-T2, two pilot symbols P1 and P2 are defined to enable fast channel searching and service discovery within the frame. Furthermore, for the carriage of Open Systems Interconnection (OSI) layer 1, physical layer (L1) and frame specific information within the P2 symbol, a P2-1 packet structure is defined. In addition to the L1 and frame specific information, the P2-1 packet may also carry OSI layer 2, data link layer (L2) signaling information (e.g. Program Specific Information/Service information (PSI/SI)) or data of the actual services.
The pilot symbol P1 may enable a fast initial scan for signals. The pilot symbol P1 may also be used to signal FFT-size and frequency offset to a receiver in the initial signal scan. In addition, the pilot symbol P1 may be used to assist in coarse frequency and coarse time synchronization of the receiver.
The pilot symbol P2 may be used for coarse and fine frequency synchronization and time synchronization in addition to initial synchronization achieved with pilot symbol P1. Moreover, the pilot symbol P2 may also carry L1 signaling information which may describe the physical parameters of the transmission and the construction of the TFS-frame. Furthermore, the pilot symbol P2 may provide an initial channel estimate, which may be needed to decode information in the P2 symbol and together with scattered pilots, the information in the first data symbols in the frame. Finally, the pilot symbol P2 may provide a channel for carrying L2 signaling information.
In the proposed DVB-T2, time frequency slicing (TFS)-related dynamic signaling is proposed to be transmitted in P2 synchronization symbols. In this arrangement, each TFS frame contains one or a limited number of P2 symbols that carry information regarding how a receiver can find desired services from the following frame. In the current proposal, dynamic signaling carried in P2 symbols is one of the key elements. However, it has been noticed that the dynamic signaling may not be sufficiently robust. Because reception without signaling is not possible, signaling robustness must be guaranteed to be better than data path robustness.
In order to improve dynamic signaling robustness, it is possible include parts of the dynamic signaling data in conjunction (i.e., being co-scheduled) with the actual data so that, when a receiver is following a service, dynamic signaling data for the received service from the same place is reduced. However, this implementation suffers from the fact that that providing co-scheduled signaling would include information about only the one service that is transmitted with the signaling. This is because, if all co-scheduled signaling contained information of all services, then required signaling capacity would be multiplied by the number of transmitted services. As such, in this arrangement, improved robustness does not result in the channel-switching scenario where the receiver needs to rely on the signaling provided only via P2 symbols.